Lens-grinding machine



m mmw.

Jan. 9, 1923,

H. W. HILL.

LENS GRINDING MACHINE.

FlLED JUNE 22,'1920. Z SHEETSSHEET 1.

' INVENTOR I HHWRV WH/u.

Jan. 9, 19230 I l/MHLSIIIS.

H. W. HILL. LENS GRINDING MACHINE.

FILED JUNE 22, 1920. 2 SHEETSSHEET 2.

IINVENTOR HRRRYW HILL BY i II MI I N M:

lEY-S til Fatented mlan; 9, lhfld tlltltil lHm HARRY W. HILL, FSOUJEHFREDGJE, MASSACHUSETTS, fltSfillGNOltt T0 AMERICAN QF'IICALCOMPANY, U15 SOUTHBRIEDGE, MASSACHUSETTS, A VOLUNTARY ASSQ- "CIATION 0FMASSAGHUSJETTS.

tnn's-enrnnrive MAGHINE.

Application filed June 22,

To all whom it may concern:

Be it known that l, HARRY W. HILL, a citizen of the United States,residing at Southbridge, in the county of Worcester and State ofMassachusetts, have inventedcertain new and useful Improvements inLens-Grinding Machines, of which the following is a specification.

This invention relates to improvements in grinding machines and hasparticular reference to a machine especially adapted for use in themanufacture of ophthalmic lenses. 1

@ne of the leading objects of the present invention is the provision ofa novel and improved construction of machine which shall besubstantially automatic in operation and which may be accurately set toproduce the particular results intended, as to produce a given curve ona blank which at the completion of the grinding operation shall be of apredetermined thickness, and in which the application of abrasive duringthe grinding operation, the stopping of the grinding operation, and thelike, shall be automatically effected.

Uther objects of the invention include a simplification and improvementin the structural details of machines of this general character, such asshould be readily apparent by reference to the following speci--fication taken in connection with the accompanying drawings, and it willbe understood that l[ may make any modifications in the specific detailsof construction shown and described within the scope of the appendedclaims without departing from or exceeding the spirit of the invention.

Figure it represents a front elevation of amachine embodying theprinciples of this invention.

Figure Ill represents a side elevation thereof.

Figure lllfll represents a plan view.

Figure IV represents a detail of the block adjusting gauge. I

In the drawings, the numeral 1 designates the main table or base portionhaving journaled therein the spindle 2 adapted to carry thelens grindingor engaging member, 3, which may be of any desired form, in the presentinstance having been shown as of convex form, having the integralabrasive receiving flange rim t and having 1920. serial no. aedeea thegroove or channed 5 formed in its face as well asthe central relievedportion 6. it would here call particular attention to the fact that thewalls of the channel 5 are shown as vertically disposed or parallel to Ithe axis of the spindle 2 rather than radial to the curve, theparticular reason for this construction being that the groove may at alltimes occupy the same position relative to the other portions of themachine irrespective of the wearingaway of the surface of the member 3,in that the member may be vertically adjusted to compensate for the wearand the position of the walls of the groove will thus hold the channelin constant relation as adjustment is made. This adjustment may be madeas by the pair of lock nuts 7 threaded on the upper end of the spindle2, a keyed washer 8 being interposed between the lock nuts and thebearing 9 on the spindle 2 to prevent accidental loosening of the partsduring rotation.

In the form of invention illustrated there is located rearwardly of thespindle 2 a raised boss 10, and preferably forwardly thereof a secondtable portion 11. The machine may be constructed either of yokeformation having supports resting on both the tables 10 and 11, or ofbracket formation, having support only upon one of the tables, aspreferred. As shown in Figure H there is secured to the table portion 1a base bracket 12 bearing the trunnion 13 on which is swingingly mountedthe bracket 14 having the bearings 15 which support the spindle 16. Thisspindle has mounted thereon the sleeve 17 held against rotation in thebracket 15 and provided with a rack portion 18 engaged by the pinion 19which has attached thereto the arm 20 bearing a weight 21 which whenswung in one direction serves to raise and hold the spindle in elevatedposition and when swung in the opposite direction serves to force thespindle downwardly. The lower end of the sleeve 17 bears against thethrust bearing 22 on the spindle. To cause rotation of the spindle thereis mounted on the upper bearing 15 the drive pulley 23 having suitabledriving connection with the spindle 16, while secured on the spindleabove said pulley is the collar 24 adjustably held in position as by theset screw 25 and bearing the adjustable stop 26 adapted to contact withthe upper face of the pulley to limit the downward movement of thespindle. A lock nut 27 having an operating handle 28 may be mounted onthe adjustable stop to secure it in desired position.

There is suitable driving connection between the pulley 23 and thespindle 16. One suitable form of such connection is illustrated inFigure I, in which the pulley has rising therefrom the pin 29 adapted tocontact with a horizontally disposed pin or arm 30 on the collar 24 sothat when the spindle is in depressed position the two pins or arms willinterlock and cause the spindle to be driven, while when the spindle israised elevation of the collar will move the pins 29 and 30 out ofengagement to automatically stop rotation of the spindle. The mechanismillustrated in Figure I is particularly adapted for use in the grindingof bifocal lens blanks or the like in which it is desired -to leave acentral portion of the glass temporarily unabraded, the blank spinningabout the groove 5 as a center so that this portion of the blank 31 willbe unground while the surrounding portion striking the tool at the sidesof the groove will be ground. For most efficient operation of themachine in this manner it is preferred that the lens be substantiallyrigidly held upon the spindle 16, while if the same be rigidly held itis necessary in order that the curve be reproduced from the lap that thespindle be radial to the lap and to suitably adjust the bracket 14 onits trunnion 13 there may be employed the adjusting screw 32 carried bythe bracket 14 and engaging the boss 10,

- a vernier 33 serving to indicate the angular adjustment if desired.vVhen the parts have been properly adjusted the machine may be operatedif desired without the use of the stop merely by inspection of anoperator from time to time, or the machine may be set with the stop tooperate automatically.

To supply abrasive to the lenses 31 during the grinding operation theymay be either manually fed or automatically, as by the scrapers 38riding in the abrasive groove 39 within the rim 4:,these scrapers beingcarried as by a cross arm 4C0 extending from the table portion 10 to thetable portion 11 intermediate the pair of bracket arms 14. This crossarm may also be employed to receive the tool height gauge. It is to beunderstood in connection with the use of a tool such as shown in FigureI for example, that if the machine is to be set at different angles fordifferent tools, in order to maintain the center of the spindle alinedwith the center of the surface interrupted by the groove 5, it isnecessary that said surface be on line with the axis about which thebracket 14 swings. While a tool will not wear appreciabiy during thegrinding of several lenses to an extent requiring any compensating ad- Lla-1,806

justment, eventually the tool will wear off slightly so it is desirableto re-adjust it vortically, this being accomplished as previouslymentioned through the use of the lock nuts 7 on the spindle Tofacilitate a determination of the amount of adjustment required, toenable the operator at all times to determine whether or not the tool isproperly adjusted, and to assist in its vertical calibration, there maybe secured to the bar 40 the plate 41, hearing the guide 4-2 for theslide plunger 43, having pivoted to its lower end a shoe 44 adapted tospan the central recess 6 of the tool surface and rest thereagainst. Theplunger 4:3 has its upper end adapted to contact with the arm 49 of thepointer 4:5 intermcdiately pivoted to the bracket 46 on the member 4-2and riding over the indicator segment at? carried by said member 42.This device is calibrated for the particular curve of tool bcin femployed and measures accurately the height of the tool with respect tothe fulcrum point or axis about which the bracket 1.4 turns, indicatingany variation of the tool from the correct height and indicating when ithas been properly adjusted. This device may either be left permanentlyin place on the arm 40 or may be temporarily applied, as preferred. Ifpermanently in place means such as a latch a8 is preferably used to holdit in temporarily elevated position to prevent undue grinding away ofthe shoe e l; through constant contact with the tool 3.

Particular attention is called to the formation of the central recess 6in the surface of the grinding tool, this recess being of size that theblank 31 being opcraicdupon will just overlap the edge of the recessinwardly. The purpose of this recess is to permit of equal wear of thetool, since were the tool solid at the center and the lens blank notoverlapping the center the upper portion of the tool would be worn downmore rapidly than the center of the tool, making it more difiicult togauge and adjust the center of the tool, and also causing more or lessof a bump bevelling off the edge of the lens being ground. lrVit-h thetool constructed as shown, however, the wear should be substantiallyuniform and no protuberance left at the center of the tool.

I claim:

1. In a machine of the character described, the combination with atable, of: a spindle rotatable therein, a lens grinding member carriedby the spindle and having an annular groove, the walls of said groovebeing parallel to the axis of the spindle, an arm carried by the tableand overhanging the spindle in spaced relation thereto, a contactindicator carried by the arm for engagement with the lens grindingmember. and means for axially adjusting the spindle to shift the lensgrinding member into cormenace rect operative position as denoted by theindicator.

2. A. machine of the character described, including a base portion, aspindle centrally journaled therein, trunnions carried by the baseportion and equally spaced from the spindle, and a yoke member pivotallymounted on the trunnions, said yoke memher being centrally provided Withspindle receiving bearings, a spindle contained within the bearings forcooperation With the spindle of the base, means for angularly adjustingthe yoke to vary the relationships of the spindles, said adjusting meansineluding a lateral projection carried by the yoke, a threaded adjustingdevice carried by the projection and engaging" the base for rocking theyoke on its trunnions, means for adjusting the centrally journaledspindle axially, and means for indicating said adjustment.

3. A machine of the character described, including a base portion, aspindle centrally journaled therein, trunnions carried by the baseportion and equally spaced from the spindle, a yoke member pivotallymountedof the base, a sleeve on each of the second mentioned spindles, arack on the sleeves, a movable arm carried by the yokes, a pinionactuated by movement of the arm contacting with the rack for actuallymoving said spindles, and means for angularly adjusting the yoke to varythe relationships of the spindles, said adjusting means including alateral projection carried by the yoke, and a threaded adjusting devicecarried by the projection and engaging the base for rotating the yoke onits trunnion.

In testimony whereof l have aihxed my signature, in presence of twoWitnesses.

HARRY Wl-lllili. lWitnesses:

Anion G. Hasirnnn, Esrnnn M. LArLEn. V

